The tribe sued the state over income taxes assessed on members who are employed by the tribe and live on tribal land. The state raised a sovereign immunity defense and the 10th Circuit Court of Appeals allowed the state and the Oklahoma Tax Commission to be removed as defendants.

However, the court said the case could proceed against officials on the tax commission. The state asked the Supreme Court to overturn the ruling but the justices without comment declined to review the dispute in Kemp v. Osage Nation.

The lawsuit has not been decided on the merits. At issue is whether Osage County, where the tribe is based, is considered Indian Country. If that's the case, then the state cannot impose income taxes on members who are employed by the tribe and live on the reservation.